A new experiment may seem too odd to be true: Scientists have found a way to grow an eye in a tadpole’s gut. The view from the third eye is probably unappealing, but the study shows how electric charges can be used to coax cells to grow in surprising ways.

It also offers a new look at a possible way to regenerate, or regrow, larger limbs. Michael Levin, a biologist at Tufts University in Medford, Mass., led the study. He told Science News that people who have lost arms or legs may one day ...